Heat energy conversion apparatus

ABSTRACT

A heat energy conversion apparatus having a heat exchanger into which a heating fluid is introduced and an inlet and an outlet for a gaseous second fluid that is to be heated and pressurized by heat transfer from the heating fluid. The heat exchanger outlet is connected to the inlet of a gas motor, and the heat exchanger inlet is connected to the outlet of a gas pump driven by the gas motor. The gas motor removes the heated gaseous second fluid from the heat exchanger at a higher volumetric flow rate than the pump delivers the gaseous second fluid in its unheated state into the heat exchanger.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to an apparatus for converting heat into mechanical energy.

[0003] 2. Prior Art

[0004] Various arrangements have been proposed heretofore for converting waste heat, such as from an internal combustion engine, into useful mechanical energy. For example, U.S. Pat. No. 4,069,672 to Milling discloses taking part of the ammonia in an engine's water-ammonia coolant to run a turbine. Other arrangements for similar purposes are disclosed in Murphy 4,019,325, Wang 4,472,939, Arvola et al 4,800,722, and ElDifrawi 4,266,404.

SUMMARY OF THE INVENTION

[0005] The present invention is directed to a novel apparatus for converting heat energy, typically waste heat, into mechanical energy that can be used for any chosen purpose.

[0006] In accordance with this invention, a heating fluid, such as hot air, is introduced into a heat exchanger where it heats a cooler gaseous second fluid, such as ambient air, that is pumped into the heat exchanger by a gas pump, and after being heated and pressurized in the heat exchanger drives a gas motor. The gas motor drives the pump as well as one or more other load devices performing useful work. The gas motor passes the heated, pressurized gaseous second fluid from the heat exchanger at a higher volumetric flow rate than the pump is introducing it in its unheated state into the heat exchanger. This volumetric flow rate difference is achieved either by the particular drive arrangement from the gas motor to the gas pump that provides a mechanical advantage of the motor over the pump or by the comparative sizes of the two

[0007] A principal object of this invention is to provide a novel and advantageous apparatus for converting heat energy into useful mechanical energy.

[0008] Another object of this invention is to provide such an apparatus of relatively simple construction using operating components of ready availability that have proved their reliability in a wide variety of other applications.

[0009] Further objects and advantages of this invention will be apparent from the following detailed description of certain presently preferred embodiments thereof, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a schematic cross-sectional view of a first embodiment of this invention;

[0011]FIG. 2 is a partial schematic cross-section showing the gas motor and the gas pump in a second embodiment of the invention; and

[0012]FIG. 3 is a view similar to FIG. 1 and showing a third embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Before explaining the present invention in detail it is to be understood that the invention is not limited in its application to the particular arrangements shown and described since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation.

[0014] Referring to FIG. 1, in broad outline this embodiment of the present invention comprises a heat exchanger 10, a gas motor 11, a gas pump 12, and an endless belt 13 driving the pump from the motor. Both the motor 11 and the pump 12 are of the type known as root pumps or roots blowers, having two high speed counter-rotating lobes of figure-eight cross-section which mesh without actually touching. When operating as a pump, this type of rotary lobe apparatus is capable of transferring gas at a relatively low compression ratio. When operating as a fluid motor, the gas pressure on its inlet side cause the figure-eight lobes to rotate. The gas motor 11 and the gas pump 12 are the same size in this embodiment of the invention. In FIG. 1 the gaseous fluid being pumped into the heat exchanger by pump 12 is unheated ambient air.

[0015] Heat exchanger 10 has chamber 14 with an inlet 15 connected directly to the outlet of pump 12 and an outlet 17 connected directly to the inlet of motor 11. Inside the heat exchanger chamber 14 is a heat transfer conduit 18 of suitable construction for heating the air or other gaseous fluid coming into chamber from pump 12. Conduit 18 may have external fins (not shown) to enhance the heat transfer effect. Conduit 18 has an inlet 19 for receiving air or other gaseous or liquid heating fluid after it has been heated by any suitable heat source, such as an automotive engine or air conditioner, the sun, or a combustible fuel. This incoming heating fluid passes along the interior of conduit 18 to an exhaust outlet 20, transferring heat to the surrounding air or other gaseous second fluid in chamber 14. Thus, it will be seen that conduit 18 provides a pathway for the heating fluid while the surrounding interior of heat exchanger 10 provides a separate pathway for the gaseous second fluid that is being pumped in by pump 12 to be heated and pressurized by heat transfer from the heating fluid in conduit 18.

[0016] As a result of its being heated, as described, the pressure of the air or other gaseous second fluid in heat exchange chamber 14 increases to a value such that this pressure causes the lobes of gas motor 11 to rotate. One of these rotary lobes is attached to a small diameter pulley 21 driving the endless belt 13. One of the rotary lobes of gas pump 12 is attached to a larger diameter pulley 22 which is driven by belt 13. This provides a mechanical advantage for motor 11 over pump 12 so that the lobes of motor 11 rotate faster than the lobes of pump 12. Consequently, the fluid motor 11 transfers the heated air or other gaseous second fluid out of the heat exchanger 10 at a higher volumetric flow rate than the pump 12 is pumping the unheated second gaseous fluid in its unheated state into the heat exchanger.

[0017] Either rotary lobe of the gas motor 11 or either rotary lobe of the gas pump 12 may be coupled to a power outlet drive arrangement to one or more external load devices (not shown).

[0018] In place of the pulleys 21 and 22 and the endless belt 13, the gas motor 11 can drive the gas pump through suitable gearing that provides the desired mechanical advantage of the motor over the pump.

[0019]FIG. 2 shows a second embodiment of this invention having a gas motor 111 that is larger than the gas pump 112, and one rotary lobe of the motor is connected directly to one smaller rotary lobe of the pump by a rigid shaft S. In this embodiment, the larger size of the motor 111 provides it the desired mechanical advantage over the pump 112, whereby the volumetric flow rate of the heated second gaseous fluid from the heat exchanger through motor 111 is higher than the volumetric flow rate of the unheated gaseous second fluid delivered to the heat exchanger by pump 112.

[0020] If desired, the conduit 18 in FIG. 1 may be omitted and the heating fluid may be introduced into the heat exchanger chamber for direct contact with the gaseous second fluid that is to be heated by heat transfer from the heating fluid. For example, the heating fluid may be hot oil droplets sprayed into the interior of the heat exchanger.

[0021] In the embodiment of FIG. 3 a feedback conduit 30 with heat-radiating fins 31 connects the outlet of gas motor 11 to the inlet of pump 12 to recirculate and cool the gaseous second fluid expelled from motor 11 and then re-introduce it to pump 12. Any other suitable cooling arrangement in place of, or in addition to, the cooling fins may be provided to lower the temperature of the gaseous second fluid before it returns to pump 12. In other respects, the embodiment of FIG. 3 is shown identical to the embodiment of FIG. 1. However, it is to be understood that the reccirculation conduit 30 may be provided with a gas motor and pump combination arranged as shown in FIG. 2.

[0022] It is to be understood that either the gas pump or the gas motor, or both, may be of a different type, either rotary or reciprocating, than the roots pump or blower shown in the drawings. 

I claim:
 1. An energy transfer apparatus comprising: a heat exchanger having an inlet for a heating fluid, said heat exchanger also providing a pathway for a gaseous second fluid in heat exchange relationship with said heating fluid having opposite ends, with an inlet at one end and an outlet at the opposite end; a gas pump having an inlet for said gaseous second fluid and an outlet connected to said inlet of said second pathway in said heat exchanger for delivering said gaseous second fluid thereto; and a gas motor having an inlet connected to said outlet of said second pathway in the heat exchanger to be driven by said gaseous second fluid after it has been heated and pressurized by heat transfer from said heating fluid in said heat exchanger, said motor being coupled to said pump to drive the latter, said motor being operative to pass the heated gaseous second fluid from the outlet of said pathway in the heat exchanger at a higher volumetric flow rate than said pump delivers said gaseous second fluid to the inlet of said pathway in the heat exchanger.
 2. An apparatus according to claim 1 wherein said gaseous second fluid is ambient air.
 3. An apparatus according to claim to claim 1 wherein said pump and said motor are the same size, and said motor is coupled to said pump through a mechanical drive providing the motor a mechanical advantage over the pump.
 4. An apparatus according to claim 3 wherein said mechanical drive comprises a pulley of one diameter on said motor, a pulley of a larger diameter on said pump, and a flexible endless belt driving said pump pulley from said motor pulley.
 5. An apparatus according to claim 3, wherein said mechanical drive comprises gearing acting between said motor and said pump.
 6. An apparatus according to claim 1 wherein said motor is larger than said pump, and further comprising a rotary shaft coupling said motor directly to said pump so that the larger size of said motor provides said higher volumetric flow rate.
 7. An apparatus according to claim to claim 2 wherein said pump and said motor are the same size, and said motor is coupled to said pump through a mechanical drive providing the motor a mechanical advantage over the pump.
 8. An apparatus according to claim 7 wherein said mechanical drive comprises a pulley of one diameter on said motor, a pulley of a larger diameter on said pump, and a flexible endless belt driving said pump pulley from said motor pulley.
 9. An apparatus according to claim 7, wherein said mechanical drive comprises gearing acting between said motor and said pump.
 10. An apparatus according to claim 2 wherein said motor is larger than said pump, and further comprising a rotary shaft coupling said motor directly to said pump so that the larger size of said motor provides said higher volumetric flow rate.
 11. An apparatus according to claim 1, wherein said second gaseous fluid is air, said pump has an ambient air inlet, and said motor has an outlet open to the surrounding air.
 12. An apparatus according to claim 1 and further comprising a conduit connecting the outlet of said motor to the inlet of said pump, and means for cooling said second gaseous second fluid in said conduit. 